As a general rule, inert carrier ingredients must be used to formulate crop protection agents such as herbicidal compounds so that farmers can apply them conveniently and safely. The choice of formulation type and inert carrier ingredients often determines to a significant extent whether the active ingredient can express its full efficacy on application.
Farmers frequently apply pre-emergence herbicides and soil insecticides by broadcasting granular formulations directly onto the soil, as described, for example in “Chemistry and Technology of Agrochemical Formulations”, edited by D. A. Knowles, Kluwer Academic Publishers, Dordrecht/Boston/London, 1998 (ISBN 0-7514-0442-8) p. 71. Granular formulations of soil-applied herbicides can provide considerable advantages under practical field conditions because planting and application can be carried out in a single operation, thus saving time and money. This application method, while convenient, does not necessarily ensure that the activity of the crop protection agent will be fully expressed.
The International Patent Application WO 92/22204 suggests that for certain benzamide herbicides such as isoxaben (N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethyxybenzamide), the mobility in the soil and/or the herbicidal efficacy can be increased by applying these compounds in the presence of cyclodextrins.
Certain carotenoid biosynthesis inhibitor herbicides are described in GB 2,087,887, EP 0 447 004 B1, WO 94/22833, EP 0 692 474 B1, EP 0 693 490 B1, EP 0 694 538 A2, EP 0 723 960 A1, WO 98/56789 and EP 0 902 026 A1. The efficacy of said herbicides when applied to the soil can sometimes be diminished due to their tendency to bind to the soil. Said binding reduces bioavailability and prevents the full expression of herbicidal activity.
It is an object of this invention to provide methods for enhancing the pre-emergence performance of said herbicidal agents. It is another object of this invention to provide solid granular or powder compositions of carotenoid biosynthesis inhibitor herbicides and at least one inert solid carrier, as well methods for the use of said compositions in the control of weeds.